The present invention relates to self-propelled robotic systems for inspecting pipelines, particularly, live gas pipelines.
Gas distribution utilities nationwide are coming under ever-increasing pressure to maintain, upgrade and efficiently operate their underground natural gas distribution and delivery system. To do so, these utilities use a vast array of technologies to monitor, inspect, repair, rehabilitate and replace their underground pipelines. More and more piping needs to be inspected due to the age of the existing urban gas-pipeline distribution network. Currently, little to no internal inspection is performed on a line that is known or assumed to be leaking in one or more locations, without at least one of them being sufficiently major to warrant immediate action. The operating company has to make a decision as to whether to spot- or section-repair the line, reline it or completely dig it up and replace it—these decisions are typically made based on in-situ evidentiary data (maps, historical repairs, leak surveys, corrosion data, etc.) to help the operator make a safe and cost-effective decision. Due to logistical and financial considerations, repairs and line replacement are only performed in the case of multiple-location or single-location leaking sections of pipeline. Most of the time though, the decision to replace and/or reline an existing gas line is not always supported by physical evidence that the line to be replaced actually needs to be replaced along its entire length, rather than just in certain stretches or maybe even only in certain spots.
The overall assessment and repair process can thus be extremely costly without the ability to judge the most cost-effective repair approach. In the US alone, over $650 million per year is spent to repair leaks of all types—giving the utilities the tools needed to make the decisions for cost-effective repair-method selection would have a drastic impact on their operations.
These pipe mains are ageing rapidly. One of the biggest tasks facing the industry is to perform in-situ inspection using a vast array of inspection sensors, so as to ascertain the state of the main prior to making decisions as to what maintenance steps to take. Information about the state of the network, both in terms of structure (pipe-integrity, corrosion, cracks, leaks, etc.), as well as process properties (pressure, flow, humidity, etc.) is desirable for maintaining pipe systems. Such data is typically only available after a local inspection survey is performed, either visually via a camera, or through other pipe-structure sensor systems (Magnetic Flux Leakage (MFL), UT, eddy-current, etc.). Based sometimes on this, but mostly on no concrete data at all, managers have to make a decision as to whether to repair, reline or replace (typically with plastic) their mains. Real-time data as to the internal state of a line would be immensely helpful to them to make a decision as to what course of action to take.